Zeroconf is a simple Java implementation of Multicast DNS Service Discovery, aka the service discovery bit of Zeroconf. Originally written as a quick hack to avoid having to use https://github.com/jmdns/jmdns, it has evolved into something that can both announce and listen for Services:
- Listens on multiple interfaces (IPv4 and IPv6)
- Network topology changes are handled transparently.
- Sent packets include only the A and AAAA records that apply to the interface they're sent on
- Requires Java 8+ and no other dependencies.
- Javadocs at https://faceless2.github.io/zeroconf/docs
- Prebuilt binary at https://faceless2.github.io/zeroconf/dist/zeroconf-1.0.2.jar
Here's a simple example which announces a service on all interfaces on the local machine:
import com.bfo.zeroconf.*;
Zeroconf zc = new Zeroconf();
Service service = new Service.Builder()
.setName("MyWeb")
.setType("_http._tcp")
.setPort(8080)
.put("path", "/path/to/service")
.build(zc);
service.announce();
// time passes
service.cancel();
// time passes
zc.close();
To set custom TTLs for each mDNS record type:
import com.bfo.zeroconf.*;
Zeroconf zc = new Zeroconf();
Service.Builder builder = new Service.Builder()
.setName("MyWeb")
.setType("_http._tcp")
.setPort(8080)
.put("path", "/path/to/service");
// Custom TTLs for each mDNS record type.
int ttl = 120;
builder.setTTL_PTR(ttl);
builder.setTTL_SRV(ttl);
builder.setTTL_TXT(ttl);
builder.setTTL_A(ttl);
builder.build(zc);
// Announce the service.
service.announce();
And to listen, either add a Listener for events or use the live, thread-safe Collection of Services.
import com.bfo.zeroconf.*;
Zeroconf zc = new Zeroconf();
zc.addListener(new ZeroconfListener() {
public void serviceNamed(String type, String name) {
if ("_http._tcp".equals(type)) {
zc.query(type, name); // Ask for details on any announced HTTP services
}
}
public void serviceAnnounced(Service service) {
// A new service has just been announced
}
});
zc.query("_http._tcp", null); // Ask for any HTTP services
// time passes
for (Service s : zc.getServices()) {
if (s.getType().equals("_http._tcp") {
// A service has been announced at some point in the past, and has not yet expired.
}
}
// time passes
zc.close();
To disable IPv6 support, and to only listen on a single network interface with a given IP address, use:
Zeroconf zc = new Zeroconf();
zc.setIPv6(false);
zc.setLocalHostName(ip);
// Add the single NIC with the given IP.
NetworkInterface nic = NetworkUtils.findIPv4NICForIP(ip);
if (nic != null) {
// Remove all configured NICs.
zc.getNetworkInterfaces().clear();
// Add the IPv4 NIC.
zc.getNetworkInterfaces().add(nic);
}
Run ant
to build the Jar in the build
directory, and javadoc in the doc
directory.